Sit back for a moment and relax a little, and think of this scenario. It's a nice, brisk, beautiful day. The sun is out and shining, there's a warm breeze blowing by, and there's not a cloud the sky. You and your friends go out to the Tennis courts, ready for a fun afternoon of just smacking the ball around, getting some exercise, and relaxing. You're in, you're prepared, you're limber and all stretched. Now the ball is coming out towards you, and you go to hit it.
But, there's a problem. You really only know one style of hitting the tennis ball, and it doesn't serve you well exactly. It can be any sort of hit really, but no matter how well you try you just don't have the power to compete fully with your opponent.
That's nothing to be ashamed of. A lot of beginners tend to have that problem in not knowing many forms that they can hit the ball with their racket. Even a lot of moderate and intermediate players who have been playing the game for a while have one or two different styles of swinging their racket.